The formation of liposomes from the hydration of lipid films is well known in the art. However, a major barrier to large scale, economic production of liposomes was the fact that the precursor lipid films had to be very thin. As a result, from a manufacturing perspective, excessive amounts of surface area were required to yield a given amount of liposomes.
The primary method of forming lipid films was by means of conventional rotary evaporation of lipid solutions in round bottom flasks. Films produced by this means were not of a uniform thickness or surface area and required at least 600 cm.sup.2 of surface area for each mmole of lipid solution. Thus, the production of liposomes from a typical desired lot, i.e., 12 mmoles of lipid, required a 50 liter flask. Moreover, liposomes formed by hydrating the uneven film, were found to have an unacceptable degree of variability. For example, when liposomes made by prior methods were used in the liposome immunoassay disclosed in U.S. Pat. No. 4,342,826, issued to Francis X. Cole, the performance of the assay was unacceptable in terms of the reproducibility of signal output and standard curves on a batch to batch basis.